1. Filed of the Invention
The present invention relates to a switching noise cancelling system in a space diversity receiving system, and more particularly to a system for removing a switching noise generated at the output of a switch in a space diversity receiving unit.
As space diversity receiving methods, there are generally two methods, i.e., a first method for detecting, from signals from two receiving antennas, a receiving signal having a higher level, and then selecting the detected receiving signal, and a second method for controlling the phases of the receiving signals from two receiving antennas to have the same phase, and synthesizing the two receiving signals. Various research into each of the methods has been carried out. From a view point of easy construction, the first method which does not require a construction for synthesis if preferred over the second method.
The present invention relates to the first method.
2. Description of the Related Art
In the first method, a switch is used to select the higher level receiving signal. Conventionally, noises are generated at the output of the switch. The noises are generated at the time of the switching operation because the voltages of the receiving signals applied to the switch are not always the same. The difference in the voltages is caused due to the difference of the characteristics of the receivers or due to a leakage current in the switch.